Nitrates can become a serious problem in beef cattle diets when consumed at high levels. Knowing how nitrates work, why they are a risk and how to manage them can help protect both your cattle and your bottom line.
Why Are High Nitrates a Problem for Beef Cattle?
When nitrates (NO3-) are consumed at low concentrations, rumen microbes can effectively convert them to nitrite (NO2) and then further to ammonia (NH3) to produce proteins. However, if nitrates are consumed at high concentrations, this metabolic process becomes overwhelmed, leading to a buildup of nitrite. This excess spills over into the bloodstream and binds to hemoglobin, reducing the blood’s oxygen-carrying capacity. The result is similar to carbon monoxide poisoning and is a medical emergency, as cattle can die quickly. If you suspect your cattle have nitrate poisoning, contact your veterinarian immediately.
When Are Nitrates the Biggest Risk?
Nitrates pose the biggest risk to cattle when plants have accumulated levels above what can be converted to plant protein – usually during stressful growing conditions such as heat stress, drought, frost and hail damage. These events result in an inhibition of the plants’ ability to process nitrates effectively. Elevated nitrate levels can also occur with excess nitrogen fertilization.
Annual crops such as canola, wheat, corn, oats, barley, sorghum, Sudan grass, millet and rye, along with common weeds like kochia, thistle, pigweed, lambs quarter, dock and sweet clover, are more susceptible to nitrate accumulation. Harvesting annual crops as dry, baled forage or greenfeed can be of particular risk as the drying process will not reduce nitrate levels. Grazing stubble fields of nitrate-accumulating plants, such as canola or corn, can also pose a danger. There is a much smaller risk of nitrate poisoning from perennial forages. Alfalfa, for example, stores nitrogen in the roots and only moves it to the rest of the plant when needed.
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